Spontaneous tumors in SENCAR mice

Area of Science:

• Toxicologic Pathology
• Carcinogenesis Research
• Animal Models in Research

Background:

• Long-term studies are crucial for understanding chemical carcinogenesis and aging.
• SENCAR mice are a sensitive model for studying skin carcinogens, but also develop spontaneous tumors.

Purpose of the Study:

• To document spontaneous tumor and nonneoplastic lesion incidence in SENCAR mice over their lifespans.
• To assess age-related tumor development in this specific mouse strain.

Main Methods:

• Observation of 305 female and 36 male SENCAR mice across six groups for 540–875 days.
• Lifespan observation (800–875 days) for 123 females and 36 males.
• Detailed recording of tumor types, nonneoplastic lesions, and survival data.

Main Results:

• Overall tumor incidence reached 65.6% in females and 69.4% in males.
• High incidence of lung papillary tumors (16–39%) in both sexes, independent of age.
• Females exhibited age-dependent mammary tumors (5.1–21.0%), while males showed frequent liver hyperplastic nodules (33.3%).
• Leukemia and forestomach papillomas were also common.

Conclusions:

• SENCAR mice exhibit a high spontaneous tumor burden, with distinct patterns in males and females.
• Lung tumors are prevalent and age-independent, whereas mammary tumors in females are age-related.
• This data provides a baseline for spontaneous tumor formation in SENCAR mice for future toxicological studies.